In general, in my opinion, this is probably the best advice just because it is so simple to understand. Adding or modifying the parts on motorcycles is not the answer to better performance. It is the rider's experience and "fitness" that matters more, at least until you reach the expert level. For the everyday rider, getting the most out of your motorcycle in it's stock condition will probably teach you more than making expensive changes before you need them.
Of course it is fun changing parts on our motorcycles, but I would bet 50% of those changes aren't actual improvements and can sometimes lead to disappointment.
While I agree with the video, it is targeted at modern bikes. The one exception to that advice I would make for vintage bikes would be new or better shocks. Much as new tires will be the one purchase that will make the most difference for any motorcycle, when a bike is 25 years old, 30 years old, or more, the best shock you can afford will make the biggest difference, it's rare that an old motorcycle will perform it's best with the original shocks.